Very heavy oils are usually produced with the aid of one of several thermally enhanced oil recovery techniques: steam injection, fire flooding and electric resistance or microwave heating. Presently, steam injection is confined to shallow reservoirs, i.e., less than 1500 ft. The energy losses associated with delivering steam to the face of a deeper oil sand can be overcome by the use of insulated pipe or by the generation of steam down-hole. However, insulated pipe is expensive and down-hole steam generators are expensive also. Fire flood and electric heating are also limited in their practical utility for deep formations.
Down-hole steam generators and other deep formation drive gas sources were thoroughly explored in the DEEP STEAM R&D project of the U.S. Department of Energy and in the Society of Petroleum Engineers/Department of Energy Second Joint Symposium on Enhanced Oil Recovery (Apr. 5-8, 1981--Tulsa, Okla.) The studies show a long term continuing unmet need for economically practical down-hole gas generator to drive heavy oil in deep formations.
It is an object of the present invention to meet such need.